attached garage

johnboy6083 · Apr 17, 2011

good morning all.

Im getting sick of working for other people, so ive decided that im gona register with a scam, and then see if i can get enough work to jack in agency stuff.

For my assesment, i intend to split tails at main head, switchfuse or 4way board with isolator and 32Amcb supplying 6mm2 swa to garage. in garage 6way board for power, lighting, future garden lighting and 110v tranny spurred off power. sockets all RCD sockets, apart from one which i want for testing RCDs ect. everything in PVC tube.

house is TNC-s

as per the title, the garage is attached, but do the requiremnts still apply for outbuildings? there is not internal access to garage from house. also ive ive got one bit of maybe extraneous (not tested yet) metalwork in the garage, but it is a tiny bit of copper pipe supplying a tap, and its half buried in a wall.
if the garage is classed as an outbuilding, then according to the brb i have to run 10mmg/y to the garage. the thing is, the house CU is only 6m away, and IMO the ground potential will be no different across that distance. i wil, run 10mm if need be, but whats your opinions on this? is a copper pipe in an outbuildiding a few m away any different to one that is 20m away in a larger house?

thanks

John

Deleted member 26818 · Apr 17, 2011

Do you think it will import an earth potential difference into the garage?

johnboy6083 · Apr 17, 2011

no. not over 6m. it will be at the same potential as the earth on the class 1 tranny for example

malcolmsanford · Apr 17, 2011

If the garage is attached to your house mate then as long as your main incoming water is bonded as per regulation 544.1.2 then it will be within your equipotential zone of the house.

The reason you need to bond back to the MET if you extend the zone to a detached building is the distance bewteen the main house and the out building, be it a couple of meters or 50 metres, is that the metal service if coming from the house, by the time it gets to the outbuilding can be of a different potential. You need therefore to make it the same potential as the house.

To be honest mate I would not put a non RCD protected socket in the garage, even if it is labelled and for test purposes. I would have no problem fitting a single non protected one next to the house CU. You may know what it is, and not plug something that can be used outside in it, but others may not.

johnboy6083 · Apr 17, 2011

malcolmsanford said:
If the garage is attached to your house mate then as long as your main incoming water is bonded as per regulation 544.1.2 then it will be within your equipotential zone of the house.

The reason you need to bond back to the MET if you extend the zone to a detached building is the distance bewteen the main house and the out building, be it a couple of meters or 50 metres, is that the metal service if coming from the house, by the time it gets to the outbuilding can be of a different potential. You need therefore to make it the same potential as the house.

To be honest mate I would not put a non RCD protected socket in the garage, even if it is labelled and for test purposes. I would have no problem fitting a single non protected one next to the house CU. You may know what it is, and not plug something that can be used outside in it, but others may not.

fair point malc. if i did have test socket, i would remove it when i move. putting one next to the CU is more hassle than its worth, as its in a kitchen cupboard, also wall space in there is very limited, and im gona be filling that up with switchfuse ect.

i know what your saying about the potential being different, but in reality? i suppose its worst case scenario (newbury?)

Deleted member 26818 · Apr 17, 2011

Technically the garage will be a place of work, and the installation will be under the control of a skilled person.
As such only socket-outlets intended to be used for mobile equipment outdoors require RCD protection.

johnboy6083 · Apr 17, 2011

i agree with both points. like i said i will remove it when i move as the house is rented. in a normal situation i would not do this for a customer for the reasons malc stated, also id never forgive myself if ifound out somebody had fried on a lawnmower from my test socket. test failed!
cheers for the confidence spin, skilled is pushing it a bit!

malcolmsanford · Apr 17, 2011

johnboy6083 said:
fair point malc. if i did have test socket, i would remove it when i move. putting one next to the CU is more hassle than its worth, as its in a kitchen cupboard, also wall space in there is very limited, and im gona be filling that up with switchfuse ect.

i know what your saying about the potential being different, but in reality? i suppose its worst case scenario (newbury?)

In reality john if your water mains is bonded, and the garage tap is fed from the house, and your taking the garage supply for the electrics also from the house, then I can't see as it's attached that your going to introduce that potential.

I assume that the spur for the tap comes of a kitchen/bathroom and just through the wall.

I remember the old Electricity Supply Regulations had a PME section and is was advised that in a PME, that even an outside tap should be sleeved when going through a wall or coming up from the ground, if fed from inside the house, but to be honest mate with RCD protection, bonding and the PME network so much more safer than 20 yrs ago I would think you are ok